This is a nice clean routine found in the S1 IS firmware (DIGIC I !). For some reason (like the used slow ARM CPU) they decided to use DMA to copy the "start of data" data into RAM. This happens very early in the boot process, no operating system is present yet. The special 0xc0xxxxxx addresses and their use bear a great resemblance to the later DIGIC equivalents, as documented by the Magic Lantern hackers http://magiclantern.wikia.com/wiki/Register_Map